1. QuarkNet and Cosmic Ray Muon Flux Experiments
Alfred Menendez and Michael Abercrombie with Dr. Marcus Hohlmann, Dept. of Physics and Space Sciences
Abstract
QuarkNet is a nation-wide outreach program run by Fermilab National Laboratory to help high-school teachers introduce their students to the world of high-energy particle physics. Teachers, students, and physicists collaborate to inform students about the science and technology behind detecting cosmic ray muons as well using that data for studies. Here we present how the QuarkNet detectors work as well as several interesting experiments measuring the flux from different detector orientations that we ran on our college campus, the studies we conducted, and some of the results that followed from them. We use scintillator paddles, photomultiplier tubes, a DAQ card, and a computer to detect and capture the data from the cosmic ray muon strikes.
Flux Orientation Study
Flux (events/m2/60 seconds)
Time UTC (hours)
Detector is horizontal (i.e. in the x-y plane)
Using data from channel 1
Flux average is about 750 events/m2/60 sec
What are Cosmic Rays?
90% are protons (other 10% are nuclei) from outside of our solar system
Cosmic rays travel at nearly the speed of light
Observed to have reached energies up to 1021 eV
Ideas about possible sources of these high-energies include:
Active galactic nuclei
Quasars
Gamma Ray Bursts
Dark Matter
How Cosmic Rays Create Muons (μ)
Cosmic rays strike the Earth’s atmosphere, undergo nuclear reactions and
produce pions (π)
Pions then decay into a muon (μ) and a muon neutrino (v).
Some muons decay into two neutrinos and an electron (e), while others last
long enough to reach the Earth’s surface.
Flux (events/m2/60 seconds)
Time UTC (hours)
Detector is vertical (i.e. in the x-z plane)
How Do We Detect Muons?
Using data from channel 1
Flux average is about 450 events/m2/60 sec
Muon passes through paddles and generates light burst in scintillator paddles
The Photo Multiplier Tube (PMT) converts light burst into electric pulse which is
read by the QuarkNet Data AcQuisition card (DAQ)
The DAQ card connects to a computer which records the data (via HyperTerminal)
Detector is horizontal
Flux is dependent on threshold of detector
Threshold is level at which DAQ card allows data to go to the computer to be recorded
Flux increases with decreasing threshold
Low threshold
Flux (events/m2/60 seconds)
High threshold
Time UTC (hours)
Photo of setup in High Energy Physics (HEP) lab at Florida Tech